Introduction: The natural and surgical history of Chiari malformation type 1 (CM-1) in pediatric patients is currently not well described. In this study we discuss the clinical and radiographic presentation and outcomes in a large cohort of pediatric CM-1 patients treated with conservative and surgical management.

Methods: The authors retrospectively reviewed 115 pediatric patients with CM-1. The average presenting age was 8 years (range 9 months to 18 years). The cohort was evenly split between genders. Twenty-five of the 115 patients underwent posterior fossa decompression (PFD) with either dural splitting or duraplasty. Patients were followed radiographically (average 44.8 months) and clinically (average 47.3 months).

Results: Most patients exhibited chiari headaches along with sleep apnea or dysphagia. Forty-three (37%) patients presented incidentally (15 asymptomatic). Twenty-five patients underwent surgery; 22 of whom either had a syrinx or central sleep apnea. Upon presentation, mean tonsillar herniation was 12mm in the total population (10mm in nonsurgical, 19.1mm in the surgical group). 96 patients had adequate radiographic follow-up and 81 were seen back in clinic. 19 patients (76%) experienced symptomatic relief with surgery. In the conservative group, of patients presenting with symptoms, 42% (18/45) improved and 54% (25/45) remained symptomatically unchanged. 89% of asymptomatic, non-operative patients had no change in symptoms. 16/17 patients with syringes underwent PFD and 14 reduced in size. One nonoperative patient developed a new syrinx on follow-up. Surgery reduced tonsillar herniation by 8.7mm (55%) and no reduction was seen in the nonsurgical group. Although more patients with tonsillopexy experienced reduction in tonsillar ectopia (68%), nearly half of patients with dural splitting also experienced decreased ectopia (48%).

Conclusions: CM-1 patients managed conservatively do not show clinical or radiographic progression. However, symptomatic patients (sleep apnea and dysphagia) presenting with significant tonsillar herniation and syrinx are potential surgical candidates that can show significant clinical and radiographic improvement

Patient Care: This study will improve patient care by elucidating the natural history of CM-1 and by describing surgical indications and outcomes of CM-1.

Learning Objectives: By the conclusion of this session, participants should be able to discuss the natural history of CM-1 as well as its possible surgical indications.

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